A new infectious virus, dubbed SARS-CoV-2 by the World Health Organization and causing COVID-19 coronavirus disease, first occurred in Wuhan, China, in Dec 2019. The virus spread around the world fairly quickly and was confirmed in Slovenia for the first time on Mar 4, 2020, with the case of a Slovenian tourist who was infected on his way back from Morocco via Italy. With a higher number of confirmed cases worldwide and their detailed study, it has been found that the new SARS-CoV-2 coronavirus is transmitted between humans by droplets, through direct contact and with continuous exposure to high indoor aerosol concentrations. The spread of the epidemic among the world's population has increased the number of measures taken to curb the epidemic, as well as the interest of experts in various fields to understand the course of the epidemic, and predict its development and consequences. Mathematical models of epidemic development are an important tool for limiting and managing an epidemic. With appropriate epidemiological models, simulations and prediction of different scenarios can be performed. However, appropriate methodology and epidemiological models must be applied.